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**Unformatted text preview: **UNIVERSITY OF CALIFORNIA College of Engineering
Department of Electrical Engineering and Computer Scences
EECS117
Midterm 1 Examination Spring 2010 T.K. Gustafson ; Kedar Patel
March 3 2010 PRINT YOUR NAME:
SID. : SIGNATURE: Do your work on the exam. If you do need to use extra sheets
attach these to the exam so that these are considered as well. Make your methods clear so that partial credits is possible. There are two problems
THE PROBLEMS ARE EACH WORTH THE SAME 2 Problem Number One Consider a transmission line with characteristic impedance of Z0 : 509 and a load of
ZL = 75 +j15OQ. A stub with characteristic impedance Z0 : 509 is connected to this
transmission line at distance if = /\/3 from the generator as shown in the ﬁgure below. For parts (a) through (e), assume: E = g and Esmb = 2.
For all parts 15 = : Use the Smith chart (on the following page) for each of the following: a) The normalized load impedance. Indicate this point as ”A” on Smith chart. Also evaluate
it analytically. 2L: [.5+/'3 b) The normalized load admittance. Indicate this point as ”B” on Smith chart. Also evalu—
ate it analytically. ’ gL; .———/——-l”: [-5 " .3
l.é—+J3 (l-$—}1{-? LP [3 _
1.25%? _ yL: nLEaDBF’J—‘1G
c) The normalized admittance yl (the load side of the stub). Indicate this point as ”C” on
Smith chart. Also evaluate it analytically. 12-; h - ,2?\
1F” (5” ”“431
“l“? 1\ 3km) = 1+ HL¢
: 3:27 ‘ l" ”L ”gulps” 3f” =Q11ss¢A'5“°)
—'. '\
NELLO=(_+ J) 311: \‘_[‘1Le§‘“
3"”2» “ﬁll; 11- hLCi'W d) The normalized admittance y2 (the generator side of the stub). Nokg $€Ui§ L‘; b/ Q6 ‘13 avail" I:
GCVCUG "c = .3‘1864- \A‘SS yw=lgqsa+h¢5é e) The normalized input admittance ym. Indicate this point as ”D” on Smith chart. vb“ 19534,: 15:11:41va " +. H3 radam 31D— f) What minimum lengths E and Esmb Will match the load to the line. Na-Lc. 0.. Must ‘96: (”a-(7 L3 6M. ”6:” CKTC/\.€, Tim's CS fob-gt E
on SUM-EM phav’c. Tin-UK Mux‘E (1° g. HS— Leah bevemd C so ( 0‘15 + .1\\
$-Eu‘o IMLHV c,a.V\.C0\ $1.? $6 vaU<* l... ‘14‘3': 'gu§@L\ length 5 = L. 115 h}
length €8th = C‘ 7:61- .mS'WN = .0 51B \\ Problem Number Two A 1 volt unit step is launched on a transmission line of length L by a source With an internal
resistance of 75 Q. The transmission line has a characteristic impedance of 50 Q. The load
resistance is 100 Q. The time delay on the line is 10 nanoseconds. The source generates a
pulse V05) of length 5 nanoseconds. Wt) 75 9 Time Delay = 10 nsec
MAM 1v *—
% R=100§2
( CREW) 20:509 L
t 5 nsec a) What is the amplitude of the ﬁrst pulse that is launched on the line. leC'J: 21V
5‘ amplitude 2 7Y5 \l b) What is the amplitude of the ﬁrst reﬂected pulse? When does it arive at the generator? FL: WG-50 so A
use \56 3 Reglcdkeﬂi ‘70ng VoK'Eacéa.
: .1. x- 1- - 1 V amplitude = 921.5 V time of arrival = 6 c) What is the voltage across the generator resistor during the presence of the ﬁrst reﬂected
pulse? A4: HM. Bmwodwv excel Amen/6 was; CoUl co e3 % \‘S “1.9.: L g j. v
\15‘ Va" 15 d) Sketch the current waveform halfway down the line for the time interval shown. liz = -La"2}
[m3] ...

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